A)125 B)130 C)120 D)135
2 answers:
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Answer:
A. T > 2.539
Step-by-step explanation:
We have a hypothesis test of the mean, with unknown population standard deviation.
The hypothesis are:
From the hypothesis we can see that the test is right-tailed, so the critical value of t should be a positive value.
The degrees of freedom can be calculated as:
The significance level is 0.01, so the critical value tc should be the one that satisfies:
Looking up in a t-table, for 19 degrees of freedom, this critical value is tc=2.539.
Answer:
0.0713 = 7.13% probability that the result is positive.
Step-by-step explanation:
Probability of a positive test:
91% of 1/650(has the disease).
7% of 1 - 1/650 = 649/650(does not have the disease). So
0.0713 = 7.13% probability that the result is positive.